This invention relates to novel couplers for use in hair coloring compositions comprising one or more oxidative hair coloring agents in combination with one or more oxidizing agents. The invention also relates to hair coloring compositions of these novel couplers and to coloring or dyeing of hair using compositions containing these couplers.
Coloration of hair is a procedure practiced from antiquity employing a variety of means. In modern times, the most extensively used method employed to color hair is to color hair by an oxidative dyeing process employing hair coloring systems utilizing one or more oxidative hair coloring agents in combination with one or more oxidizing agents.
Most commonly a peroxy oxidizing agent is used in combination with one or more oxidative hair coloring agents, generally small molecules capable of diffusing into hair and comprising one or more primary intermediates and one or more couplers. In this procedure, a peroxide material, such as hydrogen peroxide, is employed to activate the small molecules of primary intermediates so that they react with couplers to form larger sized compounds in the hair shaft to color the hair in a variety of shades and colors.
A wide variety of primary intermediates and couplers have been employed in such oxidative hair coloring systems and compositions. Among the primary intermediates employed there may be mentioned p-phenylenediamine, p-toluenediamine, p-aminophenol, 4-amino-3-methylphenol, and as couplers there may be mentioned resorcinol, 2-methylresorcinol, 3-aminophenol, and 5-amino-2-methylphenol. A majority of the shades have been produced with dyes based on p-phenylenediamine.
For providing an orange coloration to hair 2-methyl-5-aminophenol has been extensively used in combination with p-aminophenol as a primary intermediate. However, the resulting orange color on hair undergoes significant changes on exposure to light or shampooing. U.S. Pat. No. 4,065,255 and EP patent publications EP 634165 A1 and EP 667143 A1 suggest the use of 2-methyl-5-N-hydroxyethylaminophenol, 2-methyl-5-alkylaminophenol and 2-methyl-5-aminophenol as couplers. Therefore, there is a need for new orange couplers for use in oxidative hair dyeing compositions and systems.
This invention provides novel orange couplers of the formula (1): 
wherein R is selected from C1 to C2 alkyl and hydroxyethyl; R1 is hydrogen, hydroxy, nitro, halogen, C1 to C5 alkyl or haloalkyl, C1 to C5 alkoxy or cyclic alkoxy, C1 to C5 hydroxyalkyl and C1 to C5 hydroxyalkoxy; Ar is an aromatic group, preferably an aromatic group selected from a furyl, thienyl, pyridyl, phenyl, 2,3-dihydro-benzo[1,4]dioxin-5 or -6-yl or benzo[1,3]dioxol-4 or -5-yl group; and y=1 to 3. The halogen may be fluorine, chlorine, bromine or iodine, preferable fluorine or chlorine. These novel couplers are used to provide coloration to hair in which there is good dye uptake by the hair and provides shades or colors which are stable over a relatively long period of time. The novel couplers provide for dyeing of hair that provides color or shades that possess good wash fastness and do not undergo the significant changes on exposure to light or shampooing as experienced with 2-methyl-5-aminophenol.
Preferred coupler compounds of this invention are those of formula (1) 
wherein R is a methyl group, R1 is a hydrogen, hydroxy, fluoro, chloro, trifluoromethyl, methyl or methoxy group; Ar is a pyridyl, furyl or thienyl group; and y=1 to 3.
Especially preferred couplers of this invention are the following compounds:
Compound 1: 2-methyl-5-[(1H-pyrrol-2-yl-methyl)-amino]phenol,
Compound 2: 2-methyl-5-(furan-2-yl-methylamino)phenol, and
Compound 3: 2-methyl-5-(thiophen-2-yl-methylamino)phenol.
The novel coupler compounds of formula (1) of this invention are readily prepared by a reductive amination reaction of an aminophenol of formula (2) with an appropriate aromatic carboxaldehyde of formula (3) in the presence of a suitable reducing agent, such as sodium triacetoxyborohydride or sodium borohydride, according to the following reaction sequence:
wherein R, R1 and Ar are as defined hereinbefore and R is preferably a methyl group. 
As a synthesis example an aromatic carboxyaldehyde (0.03 mmole) is treated with an excess of an aminophenol of formula (2) (44.3 mg, 1.2 equiv. %; where R is methyl) in 1% AcOH-DCE (dichloroethane) (4 mL). The mixture is agitated in a reaction vessel for about 1 hour at room temperature and then sodium triacetoxyborohydride (127 mg, 0.6 mmole) is added. The mixture is agitated for about 18 hours and then Argonaut PS-MB aldehyde (100 mg, 1.26 mmole/g loading) is added. The mixture is agitated for about 1 hour, filtered and rinsed with anhydrous DCE (2 mL). To the filtrate is added water (2 mL), shaken and the water removed by pipette. The organic layer is filtered through a Chem Elute(trademark) column (Varian, 3 mL sample capacity) and washed with DCE (2xc3x972 mL). The filtrate is evaporated in vacuum to yield the target compound of Formula (1). The resulting product is analyzed by HPLC and identified by MS., and some products characterized by 1H NMR.
Compounds 1, 2, and 3 were prepared in the following Synthesis Examples 1 to 3 according to the aforedescribed reaction sequence.